The present invention generally relates to material processing methods via high speed laser crystallization, and more particularly to methods for enhancing the conversion efficiency of thin film photovoltaics by increasing crystal size and decreasing the defects of the light absorbent layer.
The conversion efficiency of thin film solar cells depends on the crystallinity of the light absorbent layer (e.g., cadmium telluride (CdTE), copper indium selenide (CIS) and copper indium gallium selenide (CIGS)). Defects such as grain boundary and point defects in current thin film photovoltaics (PVs) degrade the photon-electron conversion efficiency and transportation of electrons. Traditional crystallization techniques used in the photovoltaic (PV) industry, such as Rapid Thermal Annealing (RTA) techniques, have several limitations. These limitations can include issues regarding non-selective heating, slow crystal growth, temperature control for large crystal growth, and the need to use costly vacuum/inert gas environments. There is a need for crystallization techniques that overcome one or more of these limitations, for example by being faster, more selective or lower cost. These improved techniques can be used to create large crystals of absorbent materials for high efficiency PVs.